Currently, runWithoutInterruption still allows interruption at global shutdown, which is a required semantic for some current callers (index builds)

Separately, we need access to true uninterruptibility,

• rename opCtx->runWithoutInterruption to runWithoutInterruptionExceptAtGlobalShutdown
• add a opCtx->setIsExecutingShutdown method which makes the op immune to all forms of interruption, including global shutdown

This clarifies what opCtx->runWithoutInterruption actually did and offers an escape hatch that turns off interruption at process exit for the thread doing cleanup.

This also sets the isExecutingShutdown flag on the ops called from the shutdown task to prevent those ops from getting killed / killing themselves